American Society of Civil Engineers

Modeling a Combined Anaerobic/Anoxic Oxide and Rotating Biological Contactors Process under Dissolved Oxygen Variation by Using an Activated Sludge-Biofilm Hybrid Model

by Tzu-Yi Pai, (Asst. Prof., Dept. of Envir. Engrg. and Mgmt., Chaoyang Univ. of Technol., Wufeng, Taichung, 413, Taiwan), Shun-Hsing Chuang, (Asst. Prof., Dept. of Envir. Engrg. and Mgmt., Chaoyang Univ. of Technol., Wufeng, Taichung, 413, Taiwan), Yung-Pin Tsai, (Assoc. Prof., Dept. of Civ. Engrg., Natl. Chi Nan Univ., PuLi, Nantou, 545, Taiwan), and Chaio-Fuei Ouyang, (Prof., Grad. Inst. of Envir. Engrg., Natl. Central Univ., Chungli, 32054, Taiwan)

Journal of Environmental Engineering, Vol. 130, No. 12, December 2004, pp. 1433-1441, (doi:

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Document type: Journal Paper
Abstract: A hybrid model which incorporated a biofilm model into the general dynamic model was developed to predict the effluent quality of a combined activated sludge and biofilm process — Taiwan National Central University Process 1. The system was performed under three different dissolved oxygen (DO) conditions in the oxic tank, including 2.0, 1.0, and 0.5 mg/L. When the DO increased from 0.5 to 2.0 mg/L, the soluble biodegradable substrate (SS) and soluble phosphate (PO4) in the effluent were not significantly influenced. Their removal efficiencies were above 92 and 94%. Ammonia–nitrogen (NH3) removal efficiency increased from 36 to 83% and nitrate–nitrogen (NO3) increased from 1.7 to 2.9 mg/L. In biofilm, when the DO was 2.0 mg/L, the active autotrophic biomass (ZA) fraction was 15.7% (surface) to 12.9% (substratum). But when the DO was 0.5 mg/L, the ZA fraction became lower and the fraction was 6.2% (surface) to 3.5% (substratum). The fraction of active nonpoly-P heterotrophic biomass (ZH) in the biofilm did not vary significantly, the values were about 28–35%. ZI decreased as the DO increased. SS in the biofilm did not vary significantly and was maintained at about 2.0 mg/L. When DO increased, NO3 also increased, NH3 decreased from 13.1 to 1.8 mg/L in biofilm.

ASCE Subject Headings:
Activated sludge
Biological processes
Wastewater management
Water treatment